1. Field of the Disclosure
This specification relates to fault current limiter, and more particularly, fault current limiter, capable of preventing damage of fault current impedance unit due to fault current, by detecting the fault current flowing to the current limiting impedance unit and accordingly switching a flow path of the fault current.
2. Background of the Disclosure
In general, fault current limiters (FCLs) do not have blocking capabilities by themselves. Thus, the FCL allows the flow of limited fault current until a circuit breaker installed in a system blocks the fault current. In typical protective coordination, as illustrated in FIG. 1, for a fault F2, fault current should be blocked by a second circuit breaker CB2. When the CB2 malfunctions due to having a trouble, a first circuit breaker CB1 operates as backup protection. And, for a fault F1, fault current is blocked by the CB1. Hence, heat capacity of the conventional FCL impedance has been designed and manufactured even by taking into account a blocking time taken by the backup protection of the CB1 due to the malfunctioned CB2. In the system illustrated in FIG. 1, the backup protection of the CB1 is carried out due to the malfunctioned CB2, and thus a normal protective coordination system should operate. However, when even the CB1 to operate as the backup protection fails to block the fault current due to its malfunction, a current over a reference value flows to the impedance of the FCL which has been designed based on the conventional normal protective coordination system. Therefore, the heat capacity of the impedance of the FCL increases over a designed value. This may be likely to cause damage to the FCL and a problem even in the system.